The invention relates to an apparatus for muscle stimulation including a motor with two motor-operated drives wherein each of these drives comprises a frame and a stepping plate supported in the frame.
U.S. Pat. No. 3,540,436 A1 discloses such an apparatus. The individual drive is a three-member cam drive with a fully wrap-around cam surface. The manufacture of such a cam however requires special machinery and therefore is expensive to manufacture. In order to prevent a lift-off of the stepping plate, the stepping plate is pulled by a tension spring onto the rotating cam disc. Still, a high lift frequency may lead to lift-off of the stepping plate resulting in chatter noises.
It is therefore the object of the present invention to provide an apparatus for muscle stimulation, which can be operated at low as well as high frequencies.